Ac-dc plate refrigeration air system

ABSTRACT

An air distribution system for a vehicle eutectic holdover refrigeration plate unit provides defined air passages between a plurality of air openings all positioned at the upper end of the plates. A DC blower is associated with one air opening and at least one AC blower is associated with another air opening. When the DC blower operates, its associated opening functions as an air outlet and the opening associated with the AC blower functions as an air inlet. The reverse is true when the AC blower is operating.

United States Patent [1 1 v Rupert, Jr.

[ AC-DC PLATE REFRIGERATION AIR SYSTEM Inventor: Donald N. Rupert, Jr., Pittsburgh,

Assignee: Dole Refrigerating Company,

Chicago, 111.

Filedz Jan. 22, 1974 Appl. No.: 435,427

U.S. Cl 62/406, 62/419, 62/407, 1 62/426, 62/439 Int. Cl....' F25d 17/04 Field of Search 62/96, 406, 419, 426, 430,

[56] References Cited UNITED STATES PATENTS 8/1932 Lambert 62/426 l/1934 Kerr 1. 62/186 5/1941 Bergstrom 62/186 Dec. 3, 1974 2,560,453 Kleist 62/406 2,740,268 4/1956 Jones 62/426 2,783,623 3/1957 Dodge 62/426 2,937,510 5/1960 Allyne 62/186 Primary Examiner-William J. Wye Attorney, Agent, or Firm-Kinzer, Plyer, Dorn & McEachran 5 7 ABSTRACT An air distribution system for a vehicle eutectic holdover refrigeration plate unit provides defined air passages between a plurality of air openings all positioned at the upper end of the plates. A DC blower is associated with one air opening and at least one AC blower is associated with another air opening. When the DC blower operates, its associated opening functions as an air outlet and the opening associated with the AC blower functions as an air inlet. The reverse is true whenthe AC blower is operating.

6 Claims, 3 Drawing Figures I AC-DC PLATE REFRIGERATION AIR SYSTEM I SUMMARY OF THE INVENTION This invention relates to a vehicle eutectic plate holdover refrigeration system and in particular to a combination AC-DC blower system for moving air through defined air passages. L

A primary purpose of the invention is an eutectic plate system of the type described which operates on DC power during one portion of the day and on AC power during another portion of the day and in which the air passages within the plate system are connected to both the AC and DC blower units.

Another purpose is an eutecticv plate system having 2 air openings at the top thereof, and generally vertical parallel air passages connecting the openings, each opening alternating as either an air inlet or as an air discharge depending upon whether the AC or DC blowers are being operated.

Another purpose is an eutectic refrigeration plate system having a plurality of air passages connected to air openings at the top thereof, which air openings can function either as an inlet or as a discharge.

Another purpose is an eutectic .plate system of the type described'having greatly simplified'electrical vwirmg. i

Other purposes will appear in the ensuing specification, drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated digrammatically in the following drawings wherein:

FIG. 1 is'afront view of an eutectic holdover refrigeration system of the type described,

FIG. 2 is a section along plane 22 of FIG. 1, and

FIG. 3 is a partial view, similar to FIG. 1, showing air flow in the reverse direction.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention relates generally to an eutectic plate holdover system of the type shown in US. Pat. No. 2,875,595 and is directed to an improvement on the air system shown in copending U. S. application Ser. No. 373,669, filed June 26, 1973. In particular, the invention relates to an improved means for distributing air over the surface of the plates in which a DC blower operates during a portion of a 24-hour operating cycle and an Ac blower operates during another portion of the 24-hour operating cycle.

The plate structure shown includes an outer cover indicated generally at 10, having sides 12 and 14, a back 16, a front 18, partically cut away in FIG. 1, and a bottom 20. The cover may conventionally be made out of sheet metal as is common in the refrigeration field. Thefront portion of the cover 18 may be insulated on the inside to prevent freezing of product that might be stacked in close proximity. The support structure for the plates and cover includes corner supports 22 and a pair of spaced bottom supports, one of which is indicated at 24 in FIG. 1. The support structure also includes generally centrally located upright braces 26, there being four such braces illustrated in FIG. 2.

Positioned within the cover are a plurality, in this;

- braces 27 mounted on bottom supports 24. The plates cated in FIGS. 1 and 2, the central section of each of A the plates may have an extended or corrugated area 32,

positioned on each side of each plate, and suitably formed of aluminum or a material having the necessary heat transfer characteristics. The oppositely-directed extended areas 32 of the plates 28 and 30 are in contact with one another to define a plurality of vertically extending air passages indicated at 34 and 36. Attached to each of the vertical braces 26 are small seal members 38 which form a seal between the plate outer surfaces and the cover to define the outer air passages within the cover.

As indicated inFIGS. 1 and 3, there are three defined air paths within the cover, outside paths indicated at 40 and 42, and an interior path indicated at 44. As illustrated in FIG. 1, air is flowing downwardly, as shown by arrows 46, in the outside paths 40 and 42, and air is flowing upwardly in the inside path 44, as shown by arrows 48. In FIG. 3, the air flow is in the reverse direction and air flows upwardly, as indicated by arrows 50, in the outside paths 40 and 42, and air is flowing downwardly, indicated by arrows 52, in the inside path 44.

also have air ports 68 positioned in front of squirrel cage blowers mounted on the opposite ends of a dualshaft blower motor, shown in phantom at 70.

Thus, the top of the cover has a plurality of air openings, with each of the openings being associated with an air path. There are air moving means or an air blower mounted on top of each of the openings. Because plate systems of the type described are utilized in over-theroadvehicles,such as milk trucks or the like, the air moving means must be capable of operating either on DC power or on AC power. When the vehicle is moving over the road, the blowers operate on DC power, as that is the type of power available on a moving vehicle. However, at night, or when the vehicle is not in use on the road, customarily the blowers for the refrigeration systems are plugged into a conventional AC source at the dock. Thus, the vehicles are constantly kept cooled, but the source of power for moving the air cooled by the refrigeration system varies, depending upon whether the vehicle is moving over the road or is parked during a non-use period. In prior vehicle refrigeration systems of the type described, there has been a single air moving means, either a blower or a propeller fan, having a motor which could operate on both DC battery and transformed-down AC power, or on both DC battery and transformed-down rectified AC power. Such arrangements necessitated several electrical components with rather complicated wiring arrangements and control circuits which were not only costly, but also, at times, subject to operational failure. The present invention overcomes the disadvantage of such an electrical system by providing a DC blower and at least one AC blower, with the blowers being wired so that when the vehicle is on the road the DC blower is operative and when the vehicle is at the dock, the AC blower or blowers are operative.

In FIG. 1, when DC blower 60 is operated, air will be drawn inwardly through the ports 68 in the two AC blower assemblies, downwardly in air paths 40 and 42 between plates 28 and 30 and between the plates and cover, as indicated by arrows 46. The air flow will turn about at the bottom, as indicated by arrows 72, where the air flows beneath the plates and in the space between the bottom of the plates and the cover 20. The air will then flow upwardly, as indicated by arrows 48, in air path 44 which includes air passages 34 and 36. The air will then be discharged out of the air ports 62 in the DC blower system.

When the refrigeration system is connected to AC power, the path of air flow is reverse. Note FIG. 3. In this case, air is brought inwardly through ports 62 in the DC blower system, flows downwardly, as indicated by arrows 52, flows beneath the plates and upwardly, as indicated by arrows 50, to be discharged out of the air ports 68 in the two AC blower systems.

Holdover eutectic plate systems prior to the type shown in copending U. S. application Ser. No. 373,669 were so constructed that the air inlet was at the bottom and the air discharge was at the top. In these systems the cold air was discharged in the area of the warmest air, at the top of a truck body, but the intake air was drawn in from the area of the coolest air, at the floor of the body. A major disadvantage of such a system was that during periods when the blower was shut off by a thermostat, for example when the truck was sitting overnight with a full load, the cold air within the plate system flowed by gravity out of the bottom air inlet opening and sometimes would freeze the product being stored adjacent the bottom opening. The present invention overcomes this disadvantage by having the air inlets and discharge at the top, thus creating a cold air trap within the'cover. A major advantage which is obtained by the present arrangement, beyond overcoming the disadvantage described above, is that the air inlets pull in air from the warm strata adjacent the upper surface of the body being cooled, rather than pulling in air from the cooler strata adjacent the floor of the body.

In the previous system, with bottom air intake and top air discharge, the use of separate AC and DC squirrel-cage blowers or propeller fans at the top would give rise to serious functional problems. When the DC blower would be activated, for example, most of the air discharged out the ports associated with the DC blower would be drawn in through the ports associated with the AC blower and would pass horizontally through the top plenum chamber, thus bypassing the holdover plates and drastically reducing the cooling capacity of the system. Although gravity shutters could be used on both AC and DC blowers to prevent intake of air through the ports of the non-operating blower, such shutters would be costly and, more significantly, would be very much subject to operational failure under the rather severe treatment accorded refrigeration equipment in a delivery truck.

During the time that a vehicle using a refrigeration system of the type described herein is being driven over the road with the DC blower in operation, the doors will be periodically opened at delivery stops as product within the truck is removed. Thus, during the route run, moist air is introduced into the vehicle body. The upper areas of the plates in the downward air flow passages 40 and 42 will initially receive the moist air to be cooled and consequently will accumulate most of the frost. These areas of the plates are large and flat, and easily defrostable by liquid defrosting systems presently available, particularly so since deforsting begins at the top of the plates. At such time as the vehicle is at the dock with the AC blowers in operation, the doors will essentially remain closed and thus there will be little, if any, moist air introduced. Accordingly, there will be a minimal frost accumulation in the extended areas 32 on the plates 28 and 30, during either the DC or AC mode of blower operation.

The air from the discharge openings will be directed outwardly and by using a squirrel cage blower, rather than a propeller fan, there will be a very carefully defined high velocity stream of cold air flowing outwardly to the rear of the body from the blower, either down the center of the body or along the sides, depending upon which power system is being utilized. There will be an air circulation pattern in a horizontal strata with the cold air coming either out of the center or out of the sides and warm air being drawn in the opposite direction, with cold air falling by gravity to the floor of the body and warm air rising to the top of the body.

Whereas the preferred form of the invention has been shown and described herein, it should be realized that there may be many modifications, substitutions and alterations thereto.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

I. In a vehicle eutectic plate refrigeration system, a cover, at least one eutectic plate positioned within said cover, said cover being closed on the bottom, sides, front and rear, a plurality of air openings at the top of said cover, air passage means within said cover and associated with said plate defining air passages which extend from one of said openings, down along a portion of the plate to the bottom of the plate, and then upwardly along a different portion of the plate to another one of said openings, DC air moving means positioned at one of said air openings, which opening functions as an air discharge when said DC means is operated to move air through said air passages, and AC air moving means associated with another one of said air openings, which opening functions as an air discharge when said AC means is operated to move air through said air passages, the opening associated with said DC air moving means functloning as an air inlet when said AC means is operated and the opening associated with said AC means functioning as an air inlet when said DC means is operated.

2. The refrigeration system of claim I further characterized in that said AC air moving means and said Dc air moving means are mounted on top of said cover and adjacent one another.

3. The refrigeration system of claim 2 further characterized in that said DC air moving means is positioned generally centrally on top of said cover and is associated with one opening, there being two AC air moving terized by and including a space beneath the plate and .above the bottom of the cover in communication with all of said paths.

' 6. The refrigeration system of claim 1 further characterized in that said AC air moving means and said DC air moving means each include a blower.

=l k l 

1. In a vehicle eutectic plate refrigeration system, a cover, at least one eutectic plate positioned within said cover, said cover being closed on the bottom, sides, front and rear, a plurality of air openings at the top of said cover, air passage means within said cover and associated with said plate defining air passages which extend from one of said openings, down along a portion of the plate to the bottom of the plate, and then upwardly along a different portion of the plate to another one of said openings, DC air moving means positioned at one of said air openings, which opening functions as an air discharge when said DC means is operated to move air through said air passages, and AC air moving means associated with another one of said air openings, which opening functions as an air discharge when said AC means is operated to move air through said air passages, the opening associated with said DC air moving means functioning as an air inlet when said AC means is operated and the opening associated with said AC means functioning as an air inlet when said Dc means is operated.
 2. The refrigeration system of claim 1 further characterized in that said AC air moving means and said Dc air moving means are mounted on top of said cover and adjacent one another.
 3. The refrigeration system of claim 2 further characterized in that said DC air moving means is positioned generally centrally on top of said cover and is associated with one opening, there being two AC air moving means, one on each side of said DC air moving means, with each of said AC air moving means being associated with an opening at the top of said cover.
 4. The refrigeration system of claim 3 further characterized in that said air passage means include three separate generally parallel air paths, each of said air paths being associated with one of said air moving means.
 5. The refrigeration system of claim 4 further characterized by and including a space beneath the plate and above the bottom of the cover in communication with all of said paths.
 6. The refrigeration system of claim 1 further characterized in that said AC air moving means and said DC air moving means each include a blower. 